OK, so I found the exact cause of the 2nd buffer problem.

Surprisingly, the first patch I sent was exactly what is
needed. Surprising because I didn't have a full handle on
the problem so perhaps I got a bit lucky.

The bug (the reason I asked you to drop the patch just now)
was that the code previously did a get_bh on all bh's in a
page, but I changed it to only put_bh the ones to be written.

The minor fix for that was to only get_bh the buffer heads to
be written.

Exact problem is described in the patch changelog. Anyone who
is feeling brave please review because I'm tired and have a
headache from too much kernel debugging ;)

Tested and seems to work. Doesn't seem to leak memory.

Nick

-- 
SUSE Labs, Novell Inc.